An organic electroluminescence (referred to herein as “organic EL”) display device is arranged with a light emitting element in each pixel and displays an image by individually controlling the light emission. A light emitting element includes a structure in which a layer (referred to herein as “light emitting layer”) including an organic EL material is sandwiched between a pair of electrodes regarded as an anode electrode and a cathode electrode. The organic EL display device is arranged with one electrode as a pixel electrode for each pixel and the other electrode is arranged as a common electrode extending over a plurality of pixels, and applied with a common voltage. The organic EL display device controls light emission from a pixel by applying a voltage of the pixel electrode to each pixel with respect to the voltage of the common electrode.
Improving the extraction efficiency of light is given as an issue for self-light emitting display devices such as an organic EL display device. For example, in an organic EL display device, since light is emitted almost isotropically within a transparent light emitting layer with a relatively large refractive index, a part of the light is totally reflected by a boundary of the light emitting layer and not able to discharge the light to the exterior from the light emitting layer, which prevents improvement in light extraction efficiency
A technique is known in which light extraction efficiency is improved by arranging a protrusion shaped pattern (also referred to as “microlens”) using an organic material for example, on the display surface side with respect to a light emitting layer.
For example, an organic EL element is disclosed in the specification of U.S. Pat. No. 6,476,550 in which light extraction efficiency is improved by forming a diffraction lattice on a cathode reflective surface. A display device is disclosed in the specification of U.S. Pat. No. 8,446,093 in which a sealing layer is arranged above a pixel stacked with a reflection electrode, EL layer and common electrode, and a microlens is arranged by molding the surface of the sealing layer. In addition, a display device is disclosed in the specification of U.S. Pat. No. 8,592,833 in which a microlens is arranged between a surface of a sealing layer or organic EL layer and the sealing layer.